Stores, such as sonobuoys and countermeasures, can be deployed from vehicles, such as aircraft, surface ships, and submarines, in a variety of manners. As an example, to minimize loads on a sonobuoy during deployment, some aircraft launch systems are oriented such that stores are ejected at an aft swept angle to reduce incident air loads. This practice, however, can cause interference with structural members and increase the weight of the launcher system. Therefore, launching at 90 degrees is desirable. As a further example in the case of sonobuoys, it is desirable to store a sonobuoy in its Sonobuoy Launch Container (SLC), thereby extending shelf life of the sonobuoy, and to eject the sonobuoy directly from the SLC.
The SLC is larger in diameter than the sonobuoy itself, and the sonobuoy rests on a bottom plate of the SLC. For store deployment from an SLC to occur, both the sonobuoy and the bottom plate must be ejected through a sonobuoy launch tube before departing an aircraft. The diameter of the sonobuoy launch tube must be large enough to accommodate the bottom plate (that has a diameter that is larger than the diameter of the sonobuoy). As a result, desirable load-reducing tolerances nominally close to diameter of the sonobuoy can not be maintained, and the sonobuoy can rotate within the sonobuoy launch tube during transit.
These rotations occur due to airloads that laterally push on the sonobuoy as it begins to emerge from the sonobuoy launch tube at the bottom of the aircraft. For example, an airstream force is roughly proportional to an exposed portion of the store. As the buoy rotates and clearances are taken up, contact with the launch tube will occur at the aft bottom edge of the launch tube and upper leading edge of the sonobuoy, causing local shear and moment loads. A friction force also occurs at these upper and lower bearing surfaces.
The airloads do not keep the buoy to one side, but can cause multiple impacts to occur as the sonobuoy bangs repeatedly into the sonobuoy launch tube during exit. These impacts can possibly result in shock loading outside of levels for which the sonobuoys are qualified.
Some attempts have been made to deal with problems associated with loading on sonobuoys during launch. For example, sonobuoys are launched from P-3C Orion maritime patrol aircraft at around a 55 degree angle from vertical to avoid buoy load problems. As discussed above, use of an angled launch system can cause interference with structural members and can increase weight of the launcher system. In other air vehicles, such as the Nimrod, sonobuoys are removed from their sonobuoy launch containers and are vertically launched from smaller-diameter launch tubes.
The foregoing examples of related art and limitations associated therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.